Consider the following hypothetical aqueous reaction: A1aq2S B1aq2. A flask is charged with 0.065 mol of A in a total volume of 100.0 mL. The following data are collected: Time (min) 0 10 20 30 40 Moles of A 0.065 0.051 0.042 0.036 0.031 (a) Calculate the number of moles of B at each time in the table, assuming that there are no molecules of B at time zero and that A cleanly converts to B with no intermediates.

Verified step by step guidance

1. Step 1: Understand the reaction A(aq) -> B(aq) and note that initially, there are 0.065 moles of A and 0 moles of B.
2. Step 2: Recognize that as the reaction proceeds, the moles of A decrease and the moles of B increase by the same amount since A converts to B with no intermediates.
3. Step 3: For each time point, calculate the change in moles of A by subtracting the moles of A at that time from the initial moles of A (0.065 moles).
4. Step 4: The change in moles of A is equal to the moles of B formed at each time point. Use this to determine the moles of B at each time point.
5. Step 5: Record the moles of B at each time point: 0, 10, 20, 30, and 40 minutes.

Key Concepts

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It is based on the balanced chemical equation, which shows the ratio of moles of each substance involved. In this case, knowing the initial moles of A and the moles of B produced allows for the determination of the moles of B at various times as A is consumed.

Concentration and Molarity

Concentration refers to the amount of a substance in a given volume of solution, typically expressed in molarity (M), which is moles of solute per liter of solution. In this problem, the initial concentration of A is crucial for calculating how much of A has reacted over time and how much B has formed, as the reaction proceeds in a closed system.

Reaction Kinetics

Reaction kinetics studies the rates of chemical reactions and the factors affecting them. In this scenario, the time intervals provided allow for the observation of how the concentration of A decreases and how the concentration of B increases, illustrating the relationship between the rate of reaction and the change in concentration of reactants and products over time.